Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum
John T Armstrong Jr., MD
Gynecology Physician in Napa, CA · enumerated 2006.
Data current as of Jul 13, 2026 · sourced from CMS NPPES
National Provider Identifier
1790875995
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Registry record
Entity type Individual (Type 1)
Name John T Armstrong Jr.
Credential MD
Sex Male
Practice address 3434 Villa Ln, Suite 360, Napa, CA, 94558
Phone (707) 257-4317
Fax (707) 257-4319
Enumeration date Oct 16, 2006
Last updated in NPPES Jul 8, 2007
Taxonomy & licenses
207VG0400X Gynecology Physician Allopathic & Osteopathic Physicians · License 00C378990 (CA) Primary
MD · Doctor of Medicine: A physician who completed medical school (allopathic medicine), residency training, and state licensure.
About the MD credential
Other identifiers
| Identifier | Type | State | Issuer |
|---|---|---|---|
| ZZR0009F | Medicaid | CA | - |
What is an NPI number?
A National Provider Identifier (NPI) is a unique 10-digit number that CMS assigns to every U.S. healthcare provider and organization under HIPAA. Type 1 NPIs identify individual providers; Type 2 NPIs identify organizations. The NPI appears on insurance claims, prescriptions, and credentialing paperwork, and never changes, even if the provider moves or changes specialty.
Frequently asked questions
Is this the official NPI registry?
No. NPI Portal is a private site built on public CMS NPPES data. The official registry is npiregistry.cms.hhs.gov, operated by CMS.
What specialty is John Armstrong?
John Armstrong is registered in NPPES with the primary taxonomy of Gynecology Physician. The taxonomy code describes the provider's classification and area of specialization for claims and credentialing.
Other providers at this practice address
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Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2007-07-08.